GT500 Tach to MSD tach adapter

[charlie D]

I am installing an MSD tach adapter to the original current sensing tach.  There is a 3 pin connector at the firewall that has red w/green stripe, red, and black with white stripe or vice versa. They are pretty hard to read. On the engine side of the connector are black, black, and red. One of the black wires goes to the temp sensor and the temp gauge works. The red is( I think) ignition positive. Is the other black wire the trigger wire for the tach? I have a mess of spliced wires as I am tracking down some old work that was done for me years ago. At this time the tach will swing from 0 to peg and drop back to 0 and stay there. Hoping once I wire this up per the MSD current sensing tach instructions all will work. Second question: I read on the Pantera forum where some of these adapters have failed, one report of fire. Anyone have information? As always, thanks for your advice.
Charlie D

[Royce Peterson]

The three wires at the dash connector are for oil pressure (stock Mustang), ignition coil +, and water temperature. The + voltage to the coil comes from the ignition switch, goes through the tachometer, and then through the resistance wire to the firewall connector.

I am installing an MSD tach adapter to the original current sensing tach.  There is a 3 pin connector at the firewall that has red w/green stripe, red, and black with white stripe or vice versa. They are pretty hard to read. On the engine side of the connector are black, black, and red. One of the black wires goes to the temp sensor and the temp gauge works. The red is( I think) ignition positive. Is the other black wire the trigger wire for the tach? I have a mess of spliced wires as I am tracking down some old work that was done for me years ago. At this time the tach will swing from 0 to peg and drop back to 0 and stay there. Hoping once I wire this up per the MSD current sensing tach instructions all will work. Second question: I read on the Pantera forum where some of these adapters have failed, one report of fire. Anyone have information? As always, thanks for your advice.
Charlie D

[The Going Thing]

If you screw up you'll be having your tach serviced.   
Rocketman offers an adapter for your use.  I'll post the link below. His name is Bob. He'll be glad to help.


http://www.rccinnovations.com/index.php?show=menu-mustang-all

[Royce Peterson]

If you wire it like MSD says there is no way to screw it up and your tach is quite safe. You will need to hook up the wires as shown on the drawing. The distributor can be the stock one running points or you can substitute a Pertronix conversion. In either case you no longer use the stock coil as it is not capable of withstanding the voltage / current coming from an MSD box.

You will no longer use the factory wiring to the coil + side, it is replaced by the white wire from the MSD box as shown.

If you screw up you'll be having your tach serviced.   

[68stangcjfb]

I didn't realize you can run one that way. Looks like my 64 Falcon Sprint convertible will be getting a hidden MSD 6AL.😁

[The Going Thing]

The reason the tach is safe because the feed for the Pertronix/ MSD distributor is BEFORE the tach. Why use the MSD?  Does the engine build warrant more than a Pertronix II and coil?

[68stangcjfb]

In my case, I will have a 331 with about 450 horsepower and a 4-speed. I have the 6AL & Blaster coil lying around and I would like the rev limiter. The only thing I would have to buy is a tach adapter.

[The Going Thing]

The link I posed has the Pedometer that will work for this application. He does Cougar/Mustang products. I am running the Pertronix II and coil. I powered the module from the tach wire BEFORE the tach.  Never an issue and runs great. I have a 600 HP 427 and It'll spin to 6500 without skipping a beat.

[Royce Peterson]

The MSD provides a modern ignition that puts out enough current to weld with. It makes plug replacement a thing of the past.

I used a MSD6AL in my car so that I could remove the rev limiter chip when the car was at the muffler or alignment shop. This puts the car in Valet mode. The engine is limited to 1500 RPM so there won't be any Ferris Bueller's day off drives while the car is at the alignment shop.

It is hard on the original style Kevin Marti plug wires. They only last a couple years and then have to be replaced due to arcing.

I hid the MSD in the front of the console mounted to the firewall. The only way to see it is to get on the floor on the passenger side and look into the console area.

The reason the tach is safe because the feed for the Pertronix/ MSD distributor is BEFORE the tach. Why use the MSD?  Does the engine build warrant more than a Pertronix II and coil?

[Royce Peterson]

I've been using mine since 1994, I have no history of failure. These are sturdy, well built devices. Unless you were to expose one to high heat or mount it directly to the engine it should last forever. I would follow MSD recommendations and mount both the MSD box and the tach adapter inside the car where they are more protected than they would be under the hood.

Second question: I read on the Pantera forum where some of these adapters have failed, one report of fire. Anyone have information? As always, thanks for your advice.
Charlie D

[shelbydoug]

The MSD provides a modern ignition that puts out enough current to weld with. It makes plug replacement a thing of the past.

I used a MSD6AL in my car so that I could remove the rev limiter chip when the car was at the muffler or alignment shop. This puts the car in Valet mode. The engine is limited to 1500 RPM so there won't be any Ferris Bueller's day off drives while the car is at the alignment shop.

It is hard on the original style Kevin Marti plug wires. They only last a couple years and then have to be replaced due to arcing.

I hid the MSD in the front of the console mounted to the firewall. The only way to see it is to get on the floor on the passenger side and look into the console area.

The reason the tach is safe because the feed for the Pertronix/ MSD distributor is BEFORE the tach. Why use the MSD?  Does the engine build warrant more than a Pertronix II and coil?

The entire MSD line has a terrible reputation for reliability. It is called the  "Might  Suddenly  Die" system.

I gave up after three 6a failures where the car laying for a month, the MSD brains died.
It got so bad that the MSD tech people told me to go to another system. I obliged.

It's dependability may have to do with climate. It seems to be much more reliable in low humidity climates like Texas, Arizona, etc.

Here in the east where summertime humidity levels probably average 95%, it does not have a good track record.

Like others, I just share my experiences and experiences vary. Best to hear the bad news.

[The Going Thing]

As for the Marti wires they 'leak" new with a Pertronix II and coil.  They're fine for stock ignition but I would stay away from them otherwise.  I have heard some mixed reviews on the 6AL as well. You can't really hide them. If you're running a race car I would assume they're fine.  I was able to use a fish tape and pull the single wire through the engine feed harness boot at the firewall and it's all but hid from all but the most observant. It really boils down to your intended use.

[T-Bone68]

If you screw up you'll be having your tach serviced.   
Rocketman offers an adapter for your use.  I'll post the link below. His name is Bob. He'll be glad to help.


http://www.rccinnovations.com/index.php?show=menu-mustang-all

Thanks!  I needed that and couldn't remember where to get it.

[charlie D]

I have tracked down the two "tach" leads that are forward of the firewall. One was part of the three wire connector that had the temp gauge and a black wire that was dead headed, which I suspect was done at Shelby since they did not use the factory Ford oil pressure indicator. The other tach lead came separately thru the firewall and was the only wire exiting at that point. Both test 12V. I can reverse where they are connected and the tach behaves the same, goes to the peg and drops back. Further reading and some of your posts indicate that if the tach fails, your ignition is dead. This car starts with the tach leads connected in either configuration. I looked under the dash as best I could without removing the seat and see a three way wire connector that has leads suspiciously looking like they are part of the tach wiring. I am guessing that the tach has been bypassed as part of the ignition by this configuration. I should have added in the first mail that the tach WAS working and jsut recently failed. So, now the question changes to how do you know if your tach is toast? Should I consider rewiring to the original thru the tach for ignition or is that really subject to failure? Last, just throw in the towel and have the tach redone to more modern specs?--yeah probably what I should do but need a coax to spend the $$. 
As an aside, some of your posts have indicated problems with MSD ignition systems. I have gone the route of throwing parts at my MSD system and it is not pleasant. I live in Maryland where the summers are very humid and that may be a contributing factor. I just replaced the magnetic pick up in my current , 2nd, distributor. Car ran, then stopped cold, just like a failed 6A box. This time the box checked out OK, the coil checked OK, opened the cap of the distributor and it was part filled with water. Condensate I suspect. Have never had that problem with a distributor before. Any more problems with this system and I will switch to no MSD box and a Pertronix distributor. Just my 2 cents.
Thanks again for all your suggestions.
Charlie D

[Royce Peterson]

There should not be two tach leads coming through the firewall. If you have a second wire separate from the OEM three wire engine feed harness that wire has been added by someone.

I have tracked down the two "tach" leads that are forward of the firewall. One was part of the three wire connector that had the temp gauge and a black wire that was dead headed, which I suspect was done at Shelby since they did not use the factory Ford oil pressure indicator. The other tach lead came separately thru the firewall and was the only wire exiting at that point. Both test 12V. I can reverse where they are connected and the tach behaves the same, goes to the peg and drops back. Further reading and some of your posts indicate that if the tach fails, your ignition is dead. This car starts with the tach leads connected in either configuration. I looked under the dash as best I could without removing the seat and see a three way wire connector that has leads suspiciously looking like they are part of the tach wiring. I am guessing that the tach has been bypassed as part of the ignition by this configuration. I should have added in the first mail that the tach WAS working and jsut recently failed. So, now the question changes to how do you know if your tach is toast? Should I consider rewiring to the original thru the tach for ignition or is that really subject to failure? Last, just throw in the towel and have the tach redone to more modern specs?--yeah probably what I should do but need a coax to spend the $$. 
As an aside, some of your posts have indicated problems with MSD ignition systems. I have gone the route of throwing parts at my MSD system and it is not pleasant. I live in Maryland where the summers are very humid and that may be a contributing factor. I just replaced the magnetic pick up in my current , 2nd, distributor. Car ran, then stopped cold, just like a failed 6A box. This time the box checked out OK, the coil checked OK, opened the cap of the distributor and it was part filled with water. Condensate I suspect. Have never had that problem with a distributor before. Any more problems with this system and I will switch to no MSD box and a Pertronix distributor. Just my 2 cents.
Thanks again for all your suggestions.
Charlie D